Polyether polyols are raw materials able to be industrially produced in large quantities, and are generally used as starting materials for the production of polyurethane, together with polyisocyanates. Conventionally, basic metal hydroxides, such as potassium hydroxide (KOH), have been used as catalysts for producing the polyether polyols. However, an amount of monofunctional polyether (monol) having a terminal double bond has increased, such that a very disadvantageous problem for the production of polyurethane has occurred. On the other hand, when a double metal cyanide catalyst is used as a catalyst for production of the polycarbonate polyether polyol, not only an amount of monol may be relatively reduced, but also a rate of an addition reaction of cyclohexene oxide (CHO) or propylene oxide (PO) may be increased. Further, a polycarbonate polyether polyol prepared by using the catalyst may be processed to provide high quality polyurethanes (e.g., coatings, elastomers, sealants, foams and adhesives).
However, conventional double metal cyanide catalysts included an excessive amount of an organic complexing agent, causing environmental pollution, and had a problem of low economic efficiency due to a complicated synthesis process and a long manufacturing time originating therefrom. In addition, a relative high level of energy may be required to fix carbon dioxide, which is a very thermodynamically stable material, and, thus, there is a need to use a high activity catalyst.
Korean Patent Publication No. 10-2012-0042796 discloses that a method of preparing a solid double metal cyanide or a multi-metal cyanide catalyst is characterized by using a lactate compound as a complexing agent. However, since the catalyst is not highly selective to carbon dioxide, there is a problem that it is difficult to control functional group in an end product. In addition, Korean Patent Publication No. 10-2014-0042167 discloses a method for producing polycarbonate by copolymerizing carbon dioxide and an epoxy compound in the presence of a double metal cyanide catalyst, simultaneously comprising an organic complexing agent containing a ketone group and a hydroxyl group. In this case, it is difficult to control the functionality to the end product produced by using the catalyst, and it is also difficult to use the end product as a high-grade polyurethane material.